Condensation product of urea and formaldehyde and process of making same



Patented July 10, 1928 it V uurrao sures PATENT I OFFIIYICE. 1

atrnou sn cams AND ous'ravnwxnuna, or BASEL, swrrznnmun, Assmnoas T was FIRM: SOCIETY OF CHEMIOAL INDHSTRY IN BASLE, 0F BASEL, SWITZERLAND.

oounnusariou'rnonuo'r or vans 41in ronmammnvnn AND r'noonss on menus emu.

80 Drawing. Application mea -"na so; 1928, Serial mi. 110,529, and in Switzerland as. a, 1925.

Our invention relates the manufacture of clear condensation products of urea and formaldehyde. It comprises the process of manufacture thereof and the new products themselves as well as the application of the same in the industr of artificial materials.

In order to obtain a clear condensation product from formaldehyde and urea it has itherto been necessary to use an excess of formaldeh de in the condensation. When the molecu ar proportion of formaldehyde to urea falls below 3:1 turbid opaque masses are obtained. For instance when a mixture of two molecular proportions of commercial formaldeh do and one molecular proportion of urea is oiled a thick precipitation is produced,

In order to obtain a clear condensation product from a molecular ratio of less than 3 molecules of formaldehyde to 1 molecule of urea, it has hitherto been necessary to conduct the reaction with addition of a basic substance.

According to this invention clear condensation products of formaldehyde and urea are made with use of a minimum proportion of formaldehyde, for instance a molecular proportion of 2 of formaldehyde .to 1 of urea, by conducting the condensation in presence of active carbon, with or without the use of a substance that delays the reaction, such as analcohol, a ketone, an ester or a mixture of any of these.

It is a matter of indifference whether the suspended carbon is present during the whole course of the condensation or eliminated by filtration in the beginning or in an desired stage of the reaction. The con ens'ation roducts obtained are as clear as water and ave a notable stability as compared with that of the products .obtained by the processes hitherto usual.

According to the conditions of the reaction, such as the temperature or duration thereof, various well-characterized condensation stages can be attained by the invention. When formaldehyde and urea are shaken together at the ordinary temperature there is formed dimethylol-urea,which can be obtained in pure form after separation of the :carbon by simple evaporatlon of the iwater.

-}-'Ihis i s surprising because" hitherto dimethylol-urea has only been accessible in hgdroxide and the pasresembling honey and as clear as water,.

which is easily soluble in water and alcohol 7 and may be regarded as the first stage of condensation.

If the heating is prolonged there may be isolated a highly viscous product, which is indeed stlll soluble in water but is insoluble in alcohol and may be regarded as the second sta e of condensation.

6n continuing the heatin still further, there is finally obtained a iighly viscous product, which is soluble neither in water 'nor alcohol and constitutes the third stage of condensation. If the more or Iess viscous syru s which are produced by evaporation of the corresponding' condensation solution are maintained for a further time at a moderate temperature, such as 60100-C., gelatinization and solidification, set in and there are formed first gummy masses which become hard, clear and solid as the treatment is prolonged and ar'e-valuble as artificial materials.

The reaction can be retarded as may be desired by the addition of an alcohol, a ketone, an ether,'an ester or a mixture of any of these. Such an agent for the purpose of uct of a lower stage is being converted into one of a higher stage in the resence' of an acid or a substance which yiel so an acid. In such" a case the retarding agent revents the end point of the condensatlon o polymerization from being attained too rapidly.

The products obtained bythe invention are applicable to very various technicalpurposes according to the stage of condensa- For example, "they are useful as plastic masses, substiikev They may be 1ntion. lacquers, varnishes, tutes of horn or the corporatedwith dyestufls, filling materials,

agents imparting elasticity or the like with regard to the purpose for which they are to In the term' urea;a1so substitutions v i term formal ehyde? also the latter shall be included.

The following examples 'illustrate the in- -.vention', the parts being by'weigh'ti-f L Ewwmlej. 1

i i .60 parts of urea are dissolved in 165 parts 1 of commercial formaldehyde of percent strength; the solution is shaken with 5 parts of animalcharcoal and then filtered. The .v-f'solution'is now evaporated to d ness at a low temperature in a vacuum. cons1sts of pure eresidue dimethylol-urea. I

Ewdmple 2.

of commercial formaldehyde of 36 per cent strength, andthe solution is filtered with about 5 arts of animal charcoal. The solution is t en boiledfor some hours in a reflux-apparatus and subsequently evaporated at a low temperature in a vacuum. The

product is a syrup, clear as glass, soluble m water and alcohol (first stage of condensation). 1 e a Eaiamqrle 3.

parts of urea are dissolved in 165 parts of commercial formaldehyde of 36 per cent strength and about 5 parts of animal charcoalare added to the solution. The latter is then boiled .for a lon of commercial formaldehyde of 36 strength. The solution is filtered wlth 5-10 time in a reflux apparatus in an air-bat and the charcoal is then filtered. The condensation" product ob-' tained is soluble in water and is precipitated therefrom by alcohol (second stage of condensation). It can be worked up in known manner into solid or gelatinous polymeriza-' tion products.

l Example '4. 60 parts of urea are dissolved in 165 parts parts of animal charcoal and then heated under pressure for some hours. An oil mass, clear as crystal is' obtained, which 1s capable of being precifpitated by alcohol and water (third stage 0 condensation). This product can be worked up in known manner to solid polymerization products.

Example 5.

continued for -some hours.

. hol and is miscible wit densation proceeds veigrapid] uct er cent Y as tus; To the clear solution 0.24 part of concentrated phosphoric acid in 20 parts of waterare added while it is ho and boiling is e solution is now capable of being pr'ecipitated by alcowater. It is evaporated in a vacuum when it becomes a thick syrdp, which is hardened at a moderate temerature.' a I v a If the alcohol is omitted while retaining the rest of the conditions the same, the conand the stage at which gth'e. pro can precipitated by EICOllOlQlS- attained in a shorter time.

The phosphoric acid can be added in the cold to the solution which has been boiled for a short time, and then the water can be distilled at a low temperature in a vacuum and the substance whlch retards condensa- H H p tion thenadded. 60' parts of urea are dissolved in-165 parts Instead of ethyl alcohol another alcohol, or a ketone, an ether, or an ester, or a mixture of any of these may be used.

What we claim is:

1.. A process for the manufacture of condensation products from urea and formaldehyde, wherein the condensation is conducted in presence of active .carbon, the latter being afterwards eliminated in any desired stage of the condensation.

' 2. A process for the manufacture of clear obtained are transformed into products of higher condensation stages by heating.

6. A- process as referred to in claim 2, wherein the initial condensation products obtained are transformed into products of condensation stages by heating.

, process as referred to in claim 1,

obtained are transformed into products of higher condensation stages by heating in presence'of a substance having acid reaction. 8. A process as referred to in claim 2,

wherein the initial condensation products,

obtained are transformed into products of higher condensation stages by heating in presence of a substance having acid reaction.

9. A process as referred to in claim 1, wherein the initial condensation products 'wherein the initial condensation products time on the water-bath in a reflux apparaobtained are transformed intoproducts of are hardened by heating.

' parting elasticity and hardened by and of an organic compound retarding the reaction.

10. -A- process as'referred to in claim 2, wherein the initial condensation products obtained are transformed into products of higher condensation stages by heating in presence of a substance having acid reaction and of an organic compound retarding the reaction. i

11. A process as referred to'in claim 1, wherein the condensation products obtained are hardened by. heating."

12.. A process as referred to in claim 2,. wherein the condensation products obtained 13. A process as referred to inclaim 1, wherein the condensation products aremixed with filling materials, dyestufis, agents imparting elasticity and hardened by heating.

14. A. rocess as referred to in claim 2, wherein e condensation products are mixed with filling materials, dyestufis, agents imheating.

15. rocess for the manufactureof clear condense on products from urea and formaldehyde by using not more than two molecular'proportions of formaldehyde to one molecular proportion of urea, wherein the condensation is conducted in presence of active carbon, this latter being afterwards eliminated in an desired stage of the condensation and w erein the initial condensation products obtained are transformed into products of higher condensation stages by agents imparting elasticity and ha' ened by heating.

17. As articles of manufacture the products obtained by reacting with formaldehyde on urea in the molecular proportion of not more than 2: 1 in presence of active carbon and in the absence of catalysts, which products constitute clear viscous bodies useful as lacquers, varnishes, impregnating materials and the like and which by hardeningyield clear, solid and hard masses of hi h stability towards chemical and physical'in uences and useful asartificial materials, for instance as pllipstic masses, substitutes of horn and-the l' e.

18. As articles of manufacture the products obtained by reacting with formaldehyde on urea in the molecular proportion of not more than 2:1 in presence of active carbon and in absence of catalysts and hardened by heating, which products constitute clear, solid, hard masses of the specific gravity 1.4 and of high stability towards chemical and physical influences and useful as artificial materials, for instance plastic masses, substitute for horn and the like.

In witness whereof we have hereunto signed our names this 10th day of May, 1926.

ALPHONSE GAMS. GUSTAVE 

